The invention relates to power conservation generally, and more specifically, to an approach for managing power consumption of network devices.
Reducing power consumption has become an important issue for businesses because of environmental concerns and the rising costs of electricity. In addition to managing electricity consumption attributable to lighting and heating and air cooling systems, corporations have to manage increased electricity usage attributable to communications networks and computer systems. This includes, for example, local area networks (LANs), and all of the network devices connected thereto, such as personal computers and shared network devices, such as copiers, printers, scanners and facsimile machines.
Corporations have made significant progress in reducing power consumption through employee education programs that encourage employees to turn off their lights and personal computers when they leave work each day. The success of this approach depends upon the diligence of employees in turning off lights, computers and other equipment when not in use. Some types of equipment take a long time to power up from a powered down state. For example, it is not uncommon for personal computers to require several minutes to xe2x80x9cboot up.xe2x80x9d Other types of equipment, such as copy machines and laboratory instruments, can require even more time to complete a power up cycle. These delays can have an adverse effect on productivity in situations where large numbers of employees are waiting for equipment to power up. As a result of these long delays, many employees leave equipment on all the time.
Another approach has been to configure certain types of equipment, such as personal computers and shared network devices, with a power saving mode of operation. A power saving mode is an operating mode in which a device consumes less power, typically by shutting down one or more subsystems or services. For example, when configured with a power saving mode, personal computers typically shut down the hard disk and monitor after a specified amount of time has passed without any keyboard or mouse activity. When keyboard or mouse activity resumes, power is restored to all components and the personal computer returns to the regular power state. Other types of shared network devices may also be configured with power saving modes of operation. For example, a copier or printer may be configured to shut down certain mechanical functions, such as a fuser module, but maintain power to an electronics module that contains the controller. A copier or printer may enter a power saving mode after no request to copy or print a document has been received for a specified amount of time. When the copier or printer receives a request to copy or print a document, then power is restored to the mechanical functions so that the copying and printing functions may be performed. The use of power saving modes of operation in personal computers and other shared network devices can save a significant amount of power.
One drawback of this approach is that personal computers and shared network devices still consume power in a power saving mode, albeit at a reduced rate. Furthermore, the transition from power saving mode to regular operating mode can require several seconds or more, depending upon the particular implementation. For example, some shared network devices, such as copiers and printers, can require several minutes to xe2x80x9cwarm upxe2x80x9d, i.e., transition, from a power saving mode to a full active mode, before a document can be copied or printed. Another drawback of this approach is that many older computers and shared network devices are not configured with power saving modes of operation.
Based on the need to conserve power with networks and computer systems and the limitations in prior approaches, an approach for managing power consumption of a network device that does not suffer from the limitations of prior approaches is highly desirable.
According to one aspect of the invention, an approach is provided for managing power consumption of a network device. According to the approach, a determination is made whether one or more state change criteria for the network device are satisfied. Examples of state change criteria include, without limitation, whether the network device needs to be operating in a different operational state to perform a specified function, whether a specified function has been completed and whether a user of the network device as entered or left a building. If the one or more state change criteria are satisfied, then the network device is signaled over a communications network to cause the network device to change from a first operational state in a plurality of operational states to a second operational state in the plurality of operational states. The network device consumes a different amount of power when operating in the second operational state relative to when the network device is operating in the first operational state signal is received that indicates that a user has entered or left the building. The approach is applicable to all types of network devices including, without limitation, computers, laboratory equipment and instruments, copy machines, facsimile machines, printers, postage machines, lights and heating and air conditioning systems.
According to another aspect of the invention, a determination is made whether one or more other state change criteria for the network device are satisfied. If so, then the network device is signaled over a communications network to cause the network device to change from the second operational state to a third operational state in the plurality of operational states. The network device consumes a different amount of power when operating in the third operational state relative to when the network device is operating in the second operational state.